Fiber-reinforced resin composite materials in which a thermosetting resin, such as an epoxy resin or an unsaturated polyester resin, is reinforced with carbon fibers as reinforcing fibers, have attracted attention due to their characteristics of light weight and yet excellent heat resistance and mechanical strength, and are increasingly used in various structures, such as housings or various members of automobiles and aircraft. A known method for molding such a fiber-reinforced resin composite material produced using an epoxy resin is an autoclave method in which a material called prepreg is cured by heating in an autoclave that can be pressurized. In a known method for molding a material produced using an unsaturated polyester resin, an intermediate material called a sheet molding compound (SMC) or a bulk molding compound (BMC) is cured and molded by press molding, injection molding, or other techniques. Particularly in recent years, development of materials excellent in productivity has actively been promoted.
A known example of such molding materials is a carbon fiber-reinforced sheet-shaped molding material containing an unsaturated polyester, a vinyl monomer, a thermoplastic polymer, a polyisocyanate, a filler, a conductive carbon black, and a wide carbon fiber bundle as essential components (see, for example, PTL 1). This molding material, which provides a molded article having excellent appearance, however has a strong odor due to the use of a highly volatile styrene monomer, leading to a problem about working environment in the molding work.
Films used in production or packaging of a molding material are required to be easy to peel since the films have to be removed from the material before molding. In a material poor in the film peeling ability, a significant amount of burr is generated in molding due to insufficient thickening of the material. Such a material has poor moldability and requires a certain time for work before molding. If the molding material after peeling the film also has poor tackiness, such a material not only requires a time in work before molding but also the poor tackiness is a factor for changing the carbon fiber content in the molding material. Thus, there has been a need for a material excellent in handleability, such as film peeling ability and tackiness.